The present invention relates generally to ion mobility spectrometers and sensors, and more particularly, to ion mobility sensors and spectrometers employing corona discharge ionization sources that are used as chemical sensors.
All known commercially available ion mobility spectrometers and sensors use isotopic ionization sources. One such ion mobility spectrometer is disclosed in U.S. Pat. No. 5,047,723 entitled "Method for Detection of Foreign Matter Contents in Gases", issued Sep. 10, 1991, for example. This patent discloses the use of an ionized carrier gas containing foreign matter that is passed through chambers with different electric fields. The field currents passing through two or more chambers are measured, and corresponding signals are obtained. The amounts and relationships of these signals permit analysis of the foreign matter contained in the gasses. The ionization source disclosed in this patent is an isotopic ionization source wherein radioactive radiation derived from an Americium ionization source ionizes the carrier gas and the molecules of the foreign matter contained in it.
Isotopic materials are subject to regulation, and analysis devices, including detection devices implementing the method disclosed in the above-cited patent are not well-received by users, particularly because of the isotopic nature of the devices. In particular, U.S. government facilities are very reluctant to use ion mobility spectrometers that use isotopic ionization sources.
Therefore, it would be an advantage to have an ion mobility spectrometer that does not use an isotopic ionization source. Accordingly, it is an objective of the present invention to provide for an ion mobility spectrometer that employs a corona discharge ionization source.